CN110035853B

CN110035853B - Drill bit and method for producing a drill rod for a drill bit

Info

Publication number: CN110035853B
Application number: CN201780075234.4A
Authority: CN
Inventors: F·施罗德; R·施奈德; C·韦伯
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2016-12-23
Filing date: 2017-11-28
Publication date: 2020-09-15
Anticipated expiration: 2037-11-28
Also published as: WO2018114239A1; CN110035853A; KR20190100212A; EP3558573A1; EP3558573B1; US20210129234A1; EP3338925A1; JP2020503181A

Abstract

A drill (10) for producing a workpiece (22) with a drill hole diameter (d)₂) And a bore hole (24) having a core diameter (d)₁) The drill bit (23) of (1), the drill bit having: a cutting section (11) having one or more cutting segments (15); a drill rod section (12) having a tubular drill rod (16); and a connecting device (13) which releasably or non-releasably connects the cutting section (11) and the drill rod section (12) to one another, wherein the tubular drill rod (16) is designed as a welded spiral tube.

Description

Drill bit and method for producing a drill rod for a drill bit

Technical Field

The invention relates to a drill bit having a drill rod in the form of a helical tube and to a method for producing a drill rod in the form of a helical tube for such a drill bit.

Background

The drill head is formed from a plurality of drill head sections, which are formed as a cutting section and a drill rod section. The cutting section comprises an annular section and one or more cutting segments which are welded, soldered, screwed or otherwise suitably fixed to the annular section. The drill rod section comprises a tubular drill rod, a cover and an insertion end via which the drill bit is fixed in a tool receiver of the core drill. The drill rod is made of a tubular material or a flat strip material, which is shaped as a tube and is connected at the strip edges by a longitudinal weld seam. The cutting section and the drill rod section are releasably or non-releasably connected by means of a connecting device. In a drill head with a non-releasable connection between the cutting section and the drill rod section, the ring section of the cutting section and the drill rod may be formed integrally, alternatively the ring section may be connected to the drill rod in a material-locking manner.

During operation of the drill, the drill produces a core having a core diameter and a bore having a bore diameter in the workpiece. The cutting segments form a cutting ring having an inner diameter corresponding to the core diameter and an outer diameter corresponding to the bore diameter. While drilling, wet drilling and dry drilling differ. A drill bit for wet drilling (wet drill bit) is different in structure from a drill bit for dry drilling (dry drill bit). In wet drilling, cooling and flushing fluids are necessary, which cool the cutting section of the drill bit as a cooling fluid and carry away the drill cuttings from the drill hole as a flushing fluid. Clean cooling and flushing liquid is usually conveyed via an inner gap between the drill core and the drill rod, and used cooling and flushing liquid, which is contaminated with drill cuttings, is conducted away via an outer gap between the drill rod and the drill hole.

Wet drill bits with an inner gap between the drill core and the drill rod and an outer gap between the drill rod and the drill hole are guided during operation of the drill only via the cutting segments, the entire drill rod not having a guide. The lack of guidance of the drill rod may cause undesirable movement of the drill bit during drilling, which degrades the quality of the drilled hole. The stronger the movement of the drill bit, the greater the deviation of the geometry of the drill hole from the circular shape. Furthermore, elastic deformation of the drill rod may occur due to the core or drilling forces acting on the drill rod.

In order to improve the guidance of the drill bit, drill bits without internal and/or external slots are known, wherein cooling and flushing liquid is conveyed in the outside of the drill rod via special conveying channels. Disadvantageously, the drill rod has a large contact surface with the drill core on the inside and a large contact surface with the drill hole on the outside. The large contact surfaces on the inside and outside of the drill rod cause strong friction. The greater the friction between the drill rod and the drill core or between the drill rod and the drill hole, the smaller the drilling progress of the drill bit and the service life of the drill rod, given the same power of the core drilling machine.

Disclosure of Invention

The object of the invention is to further develop the drill head such that the stability and guidance of the drill rod during drilling, in particular during wet drilling with cooling and flushing fluids, is improved. Furthermore, the drilling progress of the drill bit should be increased and/or the service life of the drill rod should be extended.

The object is achieved by a drill bit according to the invention and by a method according to the invention for manufacturing a drill rod for a drill bit according to the invention.

The invention relates to a drill for producing a borehole having a borehole diameter and a core having a core diameter in a workpiece, comprising: a cutting section having one or more cutting segments forming a cutting ring having an inner diameter corresponding to the core diameter and an outer diameter corresponding to the bore diameter; a drill rod section having a tubular drill rod; and a connecting device which releasably or non-releasably connects the cutting section and the drill rod section to one another.

According to the invention, the drill head is characterized in that the tubular drill rod is designed as a welded spiral tube, wherein the drill rod designed as a welded spiral tube is also referred to as a spiral tubular drill rod. The welded spiral pipe has at least one helical connecting weld which serves as a reinforcing element for the drill rod and increases the rigidity of the drill rod compared to longitudinal seam welded or tubular drill rods of the same wall thickness. Alternatively, a strip material with a smaller wall thickness may be used, which in the finished drill rod has the same rigidity as a longitudinal seam welded or tubular drill rod. Thus, the use of a welded helical tube as the drill rod increases the rigidity of the drill rod during drilling operation and/or reduces the weight of the drill rod. The higher rigidity of the drill rod improves the stability of the drill rod when drilling.

The drill bit according to the present invention has: a cutting section having one or more cutting segments; a drill pipe section having a helical tubular drill pipe; and a connecting device which releasably or non-releasably connects the cutting section and the drill rod section to one another. The cutting section comprises a single cutting segment or a plurality of cutting segments arranged annularly forming a closed cutting ring and forming a cutting ring with an intermediate space. In a drill bit with a cutting section releasably connected to a drill rod section, the cutting section, in addition to the cutting section, also comprises a ring section, which can be of helical or tubular design. The connecting device is designed as a releasable or non-releasable connecting device. The connection device is releasable if the connection can be released by the user without damage, for example a plug connection, a pin connection or a screw connection. The connection device is not releasable if the user can only release the connection by damaging the connection means, for example by soldering, welding or gluing.

Preferably, the tubular drill rod is formed from N, N ≧ 1 strip-shaped material, wherein the strip edges of the strip-shaped material are connected in a material-locking manner via N, N ≧ 1 helical connecting welds. The drill rod is made of one strip (N ═ 1) or a plurality of strips (N ≧ 2), wherein the number of strips used corresponds to the number of helical connecting welds. In the production of a spiral-tube-shaped drill rod, the strip-shaped material is continuously formed into a spiral tube in a spiral manner with a constant bending radius in a forming device and is welded at the strip edges in a welding device. For spiral pipe production, both methods in a common forming and welding apparatus and methods in separate forming and welding apparatuses are known.

In a first variant, the strip-shaped material N, N ≧ 1 is formed as a flat metal sheet of constant sheet metal thickness. The auger-like drill rod is made of a flat metal plate having a constant metal plate thickness and a constant width. The flat metal sheets are formed as spiral tubes and are joined to one another at the strip edges by means of a helical connecting seam. The formed strip-shaped material has a constant wall thickness which corresponds to the sheet metal thickness of the flat sheet metal. The geometry of the helical connecting weld can be influenced by process control during welding. By feeding the weld material, for example, a helical connecting weld can be produced which projects relative to the shaped strip material on the inside of the drill rod, on the outside of the drill rod or on both the inside and the outside of the drill rod.

In a second variant, the strip-shaped material N, N ≧ 1 is configured as a flat metal plate with at least one recess. The recesses are produced in the metal sheet before the strip material is formed into a spiral tube and are used as transport channels for the necessary cooling and flushing liquid during wet drilling. In wet drilling with a drill bit, cooling and flushing fluids are required which cool the cutting section as cooling fluids and transport away the drill cuttings from the drill hole as flushing fluids. The number of recesses, the geometry of the recesses and the arrangement of the recesses on the inner and/or outer side of the drill rod may be adapted to the amount of liquid of the cooling and flushing liquid. The recess provided on the inner side of the drill rod serves for conveying clean cooling and flushing liquid, and the recess provided on the outer side of the drill rod serves for conducting away used cooling and flushing liquid, which is contaminated with drill cuttings. Since the recess is produced in the drill bit according to the invention before the strip material is shaped, the recess can be produced on the inner side of the drill rod with little production effort. In the known drill rods, the provision of the feed channel is limited to the outside of the drill rod, since in tubular drill rods recesses can only be produced on the inside of the drill rod with great manufacturing effort.

In a third variant, the strip-shaped material N, N ≧ 1 is designed as a profile metal plate with a profile cross section, wherein the profile metal plate has a metal plate thickness and a profile height. The spiral-tube drill rod is made of a plate-shaped profile metal plate. The direction of extension of the profile cross section is defined as the longitudinal direction of the plate-shaped profile metal plate. The plate-shaped profile metal plate is advantageously provided in large numbers with different profile cross sections and enables cost-effective production of a drill rod for a drill bit. Through the profile cross section, recesses are produced on the inside and outside of the drill rod, through which recesses cooling and flushing liquid can be transported. The recess provided on the inner side of the drill rod serves for conveying clean cooling and flushing liquid, and the recess provided on the outer side of the drill rod serves for conducting away used cooling and flushing liquid, which is contaminated with drill cuttings. The geometry of the profile metal sheet can be adapted to the required liquid amounts of cooling and flushing liquid.

In a preferred further development of the drill head, at least one helical tubular connecting seam of the drill rod projects relative to the shaped strip material of the helical tube, wherein the at least one projecting helical connecting seam contains a seam material. The helical connecting weld seam projecting in relation to the formed strip material of the spiral pipe improves the guidance of the drill rod during drilling. The extension of the helical connecting weld is set such that the helical connecting weld contacts the drill hole on the outside of the drill rod and/or contacts the drill core on the inside of the drill rod. By means of the projecting helical connecting weld, the drill rod has a small contact surface with the drill core and the drill hole and generates little friction. The smaller the friction on the inner side between the drill rod and the drill core or on the outer side between the drill rod and the drill hole, the higher the drilling progress of the drill bit with the same power of the core drill and the longer the service life of the drill rod. The helical connecting seam can project on the inside of the drill rod, on the outside of the drill rod or on both the inside and the outside of the drill rod relative to the formed strip material of the spiral pipe. In order to produce a helical projection of the connecting seam, a seam material is required. The weld seam material may be configured in the form of a thread, a strip or a powder.

In addition to improved guidance of the drill rod during wet drilling and dry drilling, the helical connecting weld projecting relative to the formed strip material of the spiral pipe enables improved cooling and flushing fluid transport during wet drilling. The extended helical connecting seam is used as a conveying screw for cooling and flushing fluids. It is to be noted here that the projecting helical connecting weld enables an improved liquid transport on the inside or outside of the drill rod. Clean cooling and flushing liquid is transported on the inside of the drill rod to the machining site and used cooling and flushing liquid, which is contaminated with drill cuttings, is transported away on the outside of the drill rod. The helical connecting weld serves as a conveying screw for clean cooling and flushing fluid when the direction of rotation of the drill bit and the direction of extension of the helical connecting weld on the inside of the drill rod coincide, and as a conveying screw for used cooling and flushing fluid contaminated with drill cuttings when the direction of rotation of the drill bit and the direction of extension of the helical connecting weld on the outside of the drill rod coincide.

In a preferred variant, the weld material and the N, N.gtoreq.1 strip material have the same material properties. If the weld seam material and the strip-shaped material have the same material properties, a uniform transition is produced when welding the strip edges, and the weld seam material can be joined to the strip-shaped material in a good manner.

In an alternative preferred variant, the weld seam material and the N, N ≧ 1 strip material have different material properties, wherein the weld seam material has a higher tensile strength, a higher wear resistance or a higher tensile strength and wear resistance than the strip material. In the case of a helical connecting seam projecting in relation to the shaped strip material, the connecting seam should enable guidance of the drill rod during the drill run. The smaller the gap between the helical connecting weld and the drill core on the inside of the drill rod or the gap between the helical connecting weld and the drill hole on the outside, the better the drill rod is guided. The helical connecting weld can be cut off due to friction between the helical connecting weld and the drill core on the inner side or between the helical connecting weld and the drill hole on the outer side, thereby deteriorating the guidance of the drill rod. The properties of the helical connecting weld can be influenced by using a weld material which has a higher tensile strength, a higher wear resistance or both than the strip material, so that guiding of the drill rod via the helical connecting weld is ensured as far as possible over the entire service life of the drill rod.

In a first preferred variant, the at least one extended helical connecting weld protrudes inward by an amount Δ on the inside of the drill rod_IProjecting relative to the formed strip material of the spiral tube. The helical connecting weld projecting on the inner side of the drill rod enables the drill rod to be guided via the drill core during drilling with the drill bit. Furthermore, on the inside of the drill rodThe extended helical connecting seam enables a clean cooling and flushing fluid transport to the machining point during wet drilling with the drill. If the direction of rotation of the drill bit and the direction of extension of the helical connecting weld on the inside of the drill rod coincide, the helical connecting weld serves as a conveying screw for clean cooling and flushing liquid.

In a second preferred variant, the at least one extended helical connecting weld projects beyond the outside of the drill rod by an amount Δ_AProjecting relative to the formed strip material of the spiral tube. The helical connecting weld projecting on the outside of the drill rod enables the drill rod to be guided via the drill hole when drilling with the drill bit. Furthermore, the helical connecting weld projecting on the outside of the drill rod can support the removal of used cooling and flushing fluid, which is contaminated with drill cuttings, during wet drilling with the drill bit. If the direction of rotation of the drill bit and the direction of extension of the helical connecting weld on the outside of the drill rod coincide, the helical connecting weld serves as a conveying screw for used cooling and flushing fluid that is contaminated with drill cuttings.

In a third preferred variant, the at least one helical connecting weld protrudes inward by an amount Δ on the inside of the drill rod_IAnd an overhang delta on the outside of the drill rod_AProjecting relative to the formed strip material of the spiral tube. The helical connecting weld projecting on the inside and outside of the drill rod makes it possible to guide the drill rod, when drilling with the drill bit, not only on the inside of the drill rod via the drill core but also on the outside of the drill rod via the drill hole. The helical connecting weld projecting on the inside and outside of the drill rod serves as a conveying screw for cooling and flushing fluids on the inside or on the outside of the drill rod during wet drilling. The direction of extension of the helical connecting weld is determined: whether the helical connecting weld supports liquid transport on the inside or outside of the drill rod. The helical connecting weld supports the transport of liquid on the inside of the drill rod if the direction of extension of the helical connecting weld coincides with the direction of rotation of the drill bit on the inside of the drill rod. If the connection is helicalThe direction of extension of the weld seam coincides with the direction of rotation of the drill bit on the outside of the drill rod, so that the helical connecting weld seam supports the transport of liquid on the outside of the drill rod.

According to the invention, a method for producing a drill rod for a drill bit according to the invention is characterized in that N, N ≧ 1 strip-shaped material is shaped as a spiral and is materially bonded on the strip edges by N, N ≧ 1 helical connecting welds. The method according to the invention enables the cost-effective production of a helical tubular drill rod for a drill bit. The strip-shaped material is continuously formed into a spiral tube in a spiral shape with a bending radius that remains constant in a forming device and is welded at the strip edges in a welding device.

In a preferred further development of the method, the weld material is used for connecting N, N.gtoreq.1 helical connecting welds, N.gtoreq.1 abutting strip edges of the strip material. The weld seam material is formed, for example, in the form of a wire, a strip or a powder and produces a helical connecting weld seam projecting relative to the formed strip material. By using a weld seam material when joining the abutting strip edges in a material-locking manner, a helical connecting weld seam can be produced, which projects relative to the shaped strip material. The extended helical connecting seam guides the drill rod during drilling via the drill core on the inner side of the drill rod and/or via the drill hole on the outer side of the drill rod. The geometry of the helical connecting weld can be influenced via process control during welding. The weld material can be delivered to the inside of the drill rod, the outside of the drill rod, or both the inside and outside of the drill rod.

In a particularly preferred variant of the method, the weld seam material has a higher tensile strength, a higher wear resistance or a higher tensile strength and wear resistance than the N, N ≧ 1 strip-shaped material. By using a weld material with a higher tensile strength, a higher wear resistance or a higher tensile strength and wear resistance than the strip material, the properties of the helical connection weld can be influenced, so that guiding of the drill rod via the helical connection weld is ensured as far as possible during the entire service life of the drill rod.

In an alternative, particularly preferred variant of the method, a first weld material and a second weld material are used when connecting the abutting strip edges of the N, N ≧ 1 strip-shaped material via a helical connecting weld, wherein the material properties of the first weld material differ from the material properties of the second weld material. The properties of the helical connecting weld can be influenced via the material properties of the weld material used. The first weld seam material can have, for example, the same material properties as the strip material, so that a uniform transition between the strip edges occurs during welding and the first weld seam material can be connected to the strip material in a good manner. The second weld material may, for example, have a higher tensile strength, a higher wear resistance, or a higher tensile strength and wear resistance than the strip material and improve the properties of the helical connecting weld.

Drawings

Embodiments of the invention are explained below with the aid of the figures. The figures do not necessarily depict embodiments to scale, but rather the figures for explanation are constructed in schematic and/or slightly distorted form. It is contemplated herein that various modifications and changes may be made in relation to the shape and details of the embodiments without departing from the general inventive concept thereof. The general inventive concept is not limited to the exact form or details of the preferred embodiments shown and described below or to subject matter that is limited compared to subject matter claimed in the claims. Within the given dimensional limits, values within the stated limits are also to be disclosed as limiting values and are to be used and claimed as appropriate. For the sake of simplicity, the same reference numerals are used below for identical or similar components having an identical or similar function.

Here:

fig. 1A, 1B show a first embodiment of a drill bit according to the invention in a connected state (fig. 1A) and in an unconnected state (fig. 1B), having a cutting section and a helical tubular shank section, which can be connected via a releasable connecting device;

fig. 2A, 2B show a longitudinal section through the drill rod section of the first drill bit of fig. 1 along section line a-a in fig. 1B (fig. 2A) and a detail of the drill rod of fig. 2A in an enlarged view (fig. 2B);

fig. 3 shows a second embodiment of a drill bit according to the invention with a cutting section and a helical tubular shank section, which can be connected via a non-releasable connection;

4A, 4B show a longitudinal section of the second drill bit of FIG. 3 along section line A-A in FIG. 3 (FIG. 4A) and a detail of the drill rod of FIG. 4A in an enlarged view (FIG. 4B);

FIG. 5 illustrates a third embodiment of a drill bit according to the present invention having a cutting section and a helical tubular shank section; and

fig. 6A, 6B show a longitudinal section through the third drill bit of fig. 5 along section line a-a in fig. 5 (fig. 6A) and a detail of the drill rod of fig. 6A in an enlarged view (fig. 6B).

Detailed Description

Fig. 1A, 1B show a first embodiment of a drill bit 10 according to the present invention, hereinafter referred to as first drill bit 10. The first drill bit 10 comprises a drill rod section 11, a drill rod section 12 and a connecting device 13 which releasably connects the cutting section 11 with the drill rod section 12. Here, fig. 1A shows the first drill 10 in a connected state, and fig. 1B shows the first drill 10 in an unconnected state.

The cutting section 11 comprises a ring section 14 and a plurality of cutting segments 15, which are connected to the ring section 14. The individual cutting segments 15 are arranged annularly and form a cutting ring with an intermediate space. Instead of a plurality of cutting segments 15, the cutting section 11 can also have a single cutting segment in the form of a closed cutting ring. The cutting segment 15 is welded, soldered, screwed or otherwise suitably fastened to the ring segment 14 with the ring segment 14. The drill rod section 12 comprises a helical tubular drill rod 16, a cover 17 and an insertion end 18, via which the first drill bit 10 is fixed in a tool receiver of a core drill. While drillingThe first drill bit 10 is driven by a core drill about a drill axis 19 and is moved in a drilling direction 21 parallel to the drill axis 19 into a workpiece 22 to be machined. The first drill 10 produces a workpiece 22 having a core diameter d₁And a core 23 having a bore diameter d₂The bore hole 24. The cutting segments 15 form a cutting ring having an inner diameter and an outer diameter, the inner diameter corresponding to the core diameter d₁The outer diameter corresponding to the borehole diameter d₂。

The connection device 13 is designed as a releasable connection device in the form of a combined plug connection and pin connection and comprises a first plug connection element 25, which is connected to the ring section 14, and a second plug connection element 26, which is connected to the drill rod 16. The first and second

plug connection elements

25, 26 form a plug connection and are additionally fixed via a pin connection. The plug connection comprises a plurality of pin elements 27 which are inserted into slots 28 of the T-shape. A pin element 27 is fixed on the outside of the second plug connection element 26 and a T-shaped slit 28 is provided in the first plug connection element 25. The cutting section 11 can be simply and quickly connected with the drill rod section 12 by an operator. For this purpose, the cutting section 11 is plugged by means of the first plug connection element 25 onto the second plug connection element 26 of the drill rod section 12, so that the pin element 27 is arranged in the slot 28. The cutting section 11 is moved in the drilling direction 21 and is subsequently fixed by rotation about the drill axis 19.

The drill rod 16 is designed as a welded spiral tube which is produced from a strip-shaped material 31 in the form of a flat metal sheet by forming and welding. The flat strip 31 is shaped as a spiral and is joined at the abutting strip edges via a helical connecting seam 32. The helical connecting seam 32 acts as a reinforcing element for the drill rod 18 and increases the rigidity of the drill rod 16 compared to longitudinal seam welded or tubular drill rods of the same wall thickness.

Fig. 2A, 2B show a longitudinal section through the drill rod section 12 of the first drill bit 10 of fig. 1 along the section line a-a in fig. 1B (fig. 2A) and a detail of the drill rod 16 of fig. 2A in an enlarged view (fig. 2B).

Helical connecting welds 32 extend on the outside 33 and inside 34 of drill rod 16 relative to formed strip 31. The extension of the helical connecting seam 32 on the outer side 33 of the drill rod 16 is referred to as the overhang Δ_AAnd the extension of the helical connecting weld 32 on the inner side 34 of the drill rod 16 is referred to as the inner extension Δ_I。

In order to be able to produce a helical connecting seam 32 which projects on the outer side 33, the inner side 34 or both the outer and

inner sides

33, 34 relative to the shaped strip 31, a seam material 35 must be used when welding the shaped strip 31, said seam material providing the required material volume. The weld seam material can be in the form of a powder, a wire or a strip. Furthermore, the material properties of the weld material 35 can be adapted to the desired properties of the helical connecting weld 32.

The helical connecting weld 32 improves the guidance of the drill rod 16 during drilling with the first drill bit 10. The smaller the gap between the helical connecting weld 32 and the drill hole 24 on the outer side 33 or between the helical connecting weld 32 and the drill core 23 on the inner side 34, the better the drill rod 16 is guided. The helical connecting weld 32 can be cut off due to friction between the helical connecting weld 32 and the drill hole 24 on the outer side 33 or between the helical connecting weld 32 and the drill core 23 on the inner side 34, thereby deteriorating the guidance of the drill rod 16. By using a weld material with a higher tensile strength and wear resistance than the strip material 31, the properties of the helical connecting weld 32 can be influenced, so that guiding of the drill rod 16 via the helical connecting weld 32 is ensured as far as possible over the entire service life of the drill rod 16.

Fig. 3 shows a second embodiment of a drill bit 40 according to the invention, which is referred to as second drill bit 40 in the following. The second drill head 40 comprises a cutting section 41, a shaft section 42 and a connecting device 43, which connects the cutting section 41 to the shaft section 42 in a non-releasable manner.

The cutting section 41 comprises a plurality of cutting segments 45 forming a cutting ring having an inner diameter corresponding to the core diameter d and an outer diameter₁What is, what isSaid outer diameter corresponding to the diameter d of the bore hole₂. The drill rod section 42 comprises a spiral tubular drill rod 46, a cover 47 and an insertion end 48, via which the second drill bit 40 is fixed in a tool receiver of the core drill. The cutting segment 15 is connected to the drill rod 46 in a non-releasable manner via a connecting device 43, wherein the connecting device 43 is designed as a welded, soldered or glued connection. In principle, every connection means that non-releasably connects the cutting segment 15 and the drill rod 46 is suitable.

The drill rod 46 is formed helically in the form of a welded helical tube, which is produced by forming and welding a strip-shaped material 51 in the form of a flat metal plate with recesses. The band-shaped material 51 is shaped as a spiral tube and is connected at the abutting band edges via a helical connecting seam 52.

The second drill head 40 shows a cutting section 41 with a plurality of cutting segments 45, which are non-releasably fastened to a drill rod 46 by means of a connecting device 43. Instead of a plurality of cutting segments 45, the cutting section 41 can also have individual cutting segments designed as closed cutting rings. Furthermore, the cutting section 41 may have an annular section, which is arranged between the cutting section 45 and the drill rod 46. The cutting segments 45 are welded, soldered, screwed or otherwise fixed to the ring segments in a suitable manner, and the ring segments and the drill rod 46 are releasably or non-releasably connected by means of a connecting device. The ring section can be designed like a drill rod 46 in a helical tube. However, the use of tubular ring segments of constant wall thickness in thin strip-shaped material has proven to be suitable, since a large contact surface is provided for fixing the cutting segment 45.

Fig. 4A, 4B show a longitudinal section through the second drill head 40 of fig. 3 along the section line a-a in fig. 3 (fig. 4A) and a detail of the drill rod 46 of fig. 4A in an enlarged view (fig. 4B).

The helical connecting weld 52 of the drill rod 46 projects beyond the outer side 53 of the drill rod 46 by an amount Δ_AProjecting relative to the shaped band-shaped material 51 and forming substantially flush with the shaped band-shaped material 51 on the inner side 54 of the drill rod 46. In order to produce a helical connecting seam 52 projecting on the outer side 53, a seam material 55 is used when welding the shaped strip material 51, which seam material provides the necessary material volume.

The weld seam material 55 can be formed in powder form, in wire form or in strip form. The material properties of the helical connecting weld 52 can be adapted via the material properties of the weld material 55. The weld material 55 may have the same or different material properties as the strip material 51. If the weld seam material 55 and the strip material 51 have the same material properties, a uniform transition is produced when welding the strip edges and the weld seam material 55 can be connected to the strip material 51 in a good manner. By using a weld material 55 with a higher tensile strength and/or wear resistance than the strip material 51, the properties of the helical connecting weld 52 can be influenced, so that guiding of the drill rod 46 via the helical connecting weld 52 is ensured as far as possible over the entire service life of the drill rod 46.

The second drill 40 shows a helical tubular drill rod 46 with a helical connecting weld 52 which projects on an outer side 53 of the drill rod 46 relative to the shaped band material 51 and is formed on an inner side 54 of the drill rod 46 substantially flush with the shaped band material 51. Alternatively, the helical connecting weld 52 extends inward by an amount Δ on an inner side 54 of the drill rod 46_IProjects relative to the shaped band 51 and is formed substantially flush with the shaped band 51 on the outer side 53 of the drill rod 46. A helical connecting weld 52 projecting on the inner side 54 of the drill rod 46 enables the drill rod 46 to be guided via the core 23 during drilling by means of the second drill 40. Furthermore, the helical connecting weld 52 projecting on the inner side 54 enables a clean cooling and flushing fluid feed during wet drilling. If the direction of rotation of the second drill bit 40 and the direction of extension of the helical connecting weld 52 on the inner side 54 of the drill rod 46 coincide, the helical connecting weld 52 serves as a conveying screw for clean cooling and flushing liquid.

In wet drilling with the second drill bit 40, cooling and flushing fluid is required, which cools the cutting section 45 as cooling fluid and transports away the drill cuttings from the borehole 24 as flushing fluid. The helical connecting weld 52 projecting on the outer side 53 of the drill rod 46, in addition to guiding the drill rod 46 through the borehole 24, can also support the removal of used cooling and flushing liquid that is contaminated with drill cuttings. If the direction of rotation of the second drill bit 40 and the direction of extension of the helical connecting weld 52 on the outer side 53 of the drill rod 46 coincide, the helical connecting weld 52 acts as a conveying screw for used cooling and flushing liquid that is contaminated with drill cuttings.

For the purpose of delivering clean cooling and flushing liquid to the inner side 54 of the drill rod 46, three recesses 56A, 56B, 56C, referred to as first recess 56A, second recess 56B and third recess 56C, are provided on the inner side 54 of the drill rod 46. The recesses 56A, 56B, 56C are produced in the metal sheet before the strip-shaped material 51 is formed into a coil and serve as transport channels for the necessary cooling and flushing liquid during wet drilling by means of the second drill 40. The recesses 56A, 56B, 56C are necessary in particular in the small inner gap between the core and the drill rod. The number of recesses 56A, 56B, 56C, the geometry of the recesses 56A, 56B, 56C and the arrangement of the recesses 56A, 56B, 56C on the outer side 53 and/or the inner side 54 of the drill rod 46 may be adapted to the amount of liquid of the cooling and flushing liquid.

The recesses 56A, 56B, 56C provided on the inner side 54 of the drill rod 46 are used for conveying clean cooling and flushing liquid, and the recesses provided on the outer side 53 of the drill rod 46 can support the transport away of used cooling and flushing liquid contaminated with drill cuttings. Since the recesses 56A, 56B, 56C are produced in the second drill 40 before the strip-shaped material 51 is shaped, the recesses can be produced on the inner side 54 of the drill rod 46 with little manufacturing effort.

Fig. 5 shows a third embodiment of a drill bit 60 according to the invention, which is referred to as third drill bit 60 in the following. The third drill bit 60 comprises a cutting section 61, a shaft section 62 and a connecting device 63, which connects the cutting section 61 and the shaft section 62 in a non-releasable manner.

The cutting section 61 comprises an annular section 64 and a plurality of cutting segments 65, which are welded, soldered, screwed or otherwise suitably fixed to the annular section 64 with the annular section 64. The drill rod section 62 comprises a helical tubular drill rod 66, a cap 67 and an insertion end 68, via which the third drill bit 60 is fixed in the tool receiver of the core drill.

The drill rod 66 is designed as a welded spiral tube which is produced from a strip-shaped material 71 in the form of a corrugated profiled metal sheet by forming and welding. The band-shaped material 71 is shaped as a spiral tube and is connected at the abutting band edges via a helical connecting seam 72. The helical connecting weld 71 serves as a reinforcing element for the drill rod 66.

Fig. 6A, 6B show a longitudinal section through the third drill bit 60 of fig. 5 along the section line a-a in fig. 5 (fig. 6A) and a detail of the drill rod 66 of fig. 6A in an enlarged view (fig. 6B).

The helical connecting weld 72 of the drill rod 66 is formed substantially flush with the shaped band 71 on the outer side 73 of the drill rod 66 and on the inner side 74 of the drill rod 66. The profile cross section of the strip 71 produces recesses on the outer side 73 and the inner side 74 of the drill rod 66, via which recesses cooling and flushing liquid can be transported during wet drilling by means of the third drill bit 60. The recess provided on the inner side 74 of the drill rod 66 serves for conveying clean cooling and flushing liquid, and the recess provided on the outer side 73 of the drill rod 66 serves for guiding away used cooling and flushing liquid that is contaminated with drill cuttings. The geometry of the profile metal sheet can be adapted to the amount of liquid required for wet drilling.

Claims

1. A drill (10; 40; 60) for producing a workpiece (22) with a drill hole diameter (d)₂) And a bore hole (24) having a core diameter (d)₁) The drill bit (23) of (1), the drill bit having:

-a cutting section (11; 41; 61) having one or more cutting segments (15; 45; 65) forming a cutting ring having an inner diameter and an outer diameter, the inner diameter corresponding to the core diameter (d)₁) The outer diameter corresponding to the borehole diameter (d)₂)；

-a drill rod section (12; 42; 62) having a tubular drill rod (16; 46; 66); and

-a connecting device (13; 43; 63) which releasably or non-releasably connects the cutting section (11; 41; 61) and the drill rod section (12; 42; 62) to one another;

characterized in that the tubular drill rod (16; 46; 66) is designed as a welded spiral tube.

2. Drill bit according to claim 1, characterized in that the tubular drill rod (16; 46; 66) is formed from N, N ≧ 1 strip-shaped material (31; 51; 71), wherein the strip edges of the strip-shaped material (31; 51; 71) are connected in a material-locking manner via N, N ≧ 1 helical connecting welds (32; 52; 72).

3. The drill bit of claim 2, wherein the N, N ≧ 1 strip material is constructed as a flat metal plate of constant sheet metal thickness.

4. Drill bit according to claim 2, characterized in that the strip-like material N, N ≧ 1 is constituted as a flat metal plate with at least one recess (55A, 55B, 55C).

5. Drill bit according to claim 2, characterized in that the strip-shaped material N, N ≧ 1 is constructed as a profile metal plate with a profile cross section, wherein the profile metal plate has a metal plate thickness and a profile height.

6. Drill bit according to one of claims 2 to 5, characterized in that at least one helical connecting weld of the drill rod protrudes with respect to the shaped strip material of the spiral pipe, wherein the at least one protruding helical connecting weld comprises a weld material (35; 55).

7. Drill bit according to claim 6, characterized in that the weld material (35; 55) and the N, N ≧ 1 strip-like material have the same material properties.

8. Drill bit according to claim 6, characterized in that the weld material (35; 55) and the N, N ≧ 1 strip-like material have different material properties.

9. Drill bit according to claim 8, characterized in that the weld material (35; 55) has a higher tensile strength, a higher wear resistance, or a higher tensile strength and wear resistance than the strip material.

10. Drill bit according to claim 6, characterized in that the at least one protruding helical connecting weld bead is inwardly protruding (Δ) on the inner side (54) of the drill rod_I) Projecting relative to the formed strip material of the spiral tube.

11. Drill bit according to claim 6, characterized in that the at least one extended helical connecting weld bead extends beyond (Δ) on the outer side (53) of the drill rod_A) Projecting relative to the formed strip material of the spiral tube.

12. Drill bit according to claim 6, characterized in that the at least one protruding helical connecting weld bead is inwardly protruding (Δ) on the inner side (34) of the drill rod_I) And an overhang (Delta) on the outside (33) of the drill rod_A) Projecting relative to the formed strip material of the spiral tube.

13. Method for producing a drill rod (16; 46; 66) for a drill bit (10; 40; 60) according to one of claims 1 to 12, in which method N, N ≧ 1 strip-shaped material (31; 51; 71) is shaped as a spiral and is connected in a material-locking manner on the abutting strip edges via N, N ≧ 1 helical connecting welds (32; 52; 72).

14. Method according to claim 13, characterized in that a weld material (35; 55) is used in connecting the butt-joint strip edges of the N, N ≧ 1 strip-like material via the N, N ≧ 1 helical connecting weld.

15. The method according to claim 14, characterized in that the weld material (35; 55) has a higher tensile strength, a higher wear resistance or a higher tensile strength and wear resistance than the strip material.

16. The method of claim 15, wherein a first weld material and a second weld material are used in connecting the butted edges of the N, N ≧ 1 strip material via the helical connecting weld, wherein a material property of the first weld material is different from a material property of the second weld material.